I first met Jeffrey Eugenides in a hotel elevator in Sweden at a book festival. We shared a Swedish publisher, we were suitably lonely, and so we drank together for three days. This was 2004. The year before, I had published my first novel, Politics; two years earlier, he had published his second novel, Middlesex. So, from then on, I adopted him as a moral and intellectual guide. This summer, we both happened to be in Berlin for a while. Eugenides had just handed in the corrected galleys of his third novel, The Marriage Plot. In Berlin, therefore, in the Paris Bar on Kantstrasse and Lentz on Stuttgarter Platz, we began a conversation about his fiction which – when he was back in Princeton and I was back in London – we reworked on Skype.

Eugenides's two previous novels have been conspicuous for their narrative perspectives. The narrative voice of The Virgin Suicides is that of an anonymous group of men. The narrator of Middlesex is a hermaphrodite: a first-person narrator with occasional third-person omniscience. The Marriage Plot is a new experiment for Eugenides – in that it is not so obviously experimental. The narrator is the traditional third-person novelist. And this novel tells the interrelated love story of three characters – Madeleine, Mitchell and Leonard – in the year after finishing their studies at Brown University (where Eugenides himself studied) in the early 80s.

Because Madeleine is a literature student on an American campus in the 80s, the novel is haunted by the semiotic turn in literature – the idea that no true subjective expression is possible, that all expression is only a code. In other words, this novel is presided over by the ghost of Roland Barthes: who famously once said that the novel is a death ...

And so three elements kept recurring in our conversation: the shift in narrative perspective in The Marriage Plot; the presence of Roland Barthes; and an essay I had written for the New Republic when Barthes's Mourning Diary and Preparation for the Novel had been published in America – two texts that showed how in the years before he died Barthes was involved in a meticulous rewriting and reworking of his previous ideas.

It became a conversation, in other words, about how to make a novel come alive: how to turn it from a code into a truth.

Adam Thirlwell In Berlin, as we went through your previous novels and their acrobatics, we came up with a theory that a narrative voice is a device that allows you to talk about something without which you would have been unable to do so. If so, what does this new voice let you talk about?

Jeffrey Eugenides On the face of it, the voice in the new book seems a lot less complicated than those I've used before. James Wood, in the opening paragraph of his book How Fiction Works, says the following: "The house of fiction has many windows, but only two or three doors. I can tell a story in the third person or in the first person and perhaps in the second person singular, or in the first person plural, though successful examples of these latter two are rare indeed." Well, I can't say whether Wood was thinking of The Virgin Suicides with that, but use the first person plural I did, and enjoyed it enormously. From there I went to a first-person voice endowed with the occasional omniscience of a third-person narrator. Now in The Marriage Plot I settled on a close third-person narrative voice, one that tracks the consciousness of each of my three protagonists and, hopefully, carries their inner music: the voice should sound the way my characters think. It's a more traditional novelistic narrative method, but no less difficult to write and just as much fun. Maybe more so. It stays close to my people, but now and then opens up little gaps where the author can insinuate himself – but hopefully not too obtrusively.

AT I'm not sure that's an answer to my question ...

JE I sometimes tell my students that, when you write, you should pretend that you're writing the best letter you've ever written to the smartest person you know. That way, you won't pander at all. You won't put on a false face because your smart friend would spot that in a minute. Also, with this method, you naturally gain an intimacy, even a shorthand with which to communicate. The voice for The Marriage Plot, though less acrobatic, allowed me to get out of the way a bit more, to concentrate on the person whose problems and desires I was attempting to describe. You may be right that it's not "traditional", or that the term "traditional" belies the complexity of standard novelistic technique. But it's certainly less self-referential and I felt, in writing it, a gain of honesty and a deepening – for me, at least – in psychological description.

AT I'm still not sure you've answered my question. Maybe I can be you – and put it like this. By using this marriage plot – this triangle between Mitchell, Madeleine and Leonard – you end up exploring the whole wildness of psychology: not just everyday consciousness but desire, in Madeleine, manic depression, in Leonard, and mystical experience, in Mitchell (and Leonard, in a way, too). But you also encompass the methods people have come up with to describe these various interior states: the chemical language of psychiatry, the coded language of literary theory, the mystical language of religious tracts. Yet all of them are bathed in your own medium: novelistic consciousness.

And so the important word of yours is "honesty". It reminds me of a fleeting central moment in your novel – when Mitchell reads a text by St Teresa, and thinks about descriptions of mystical visions: "You could tell the difference between someone making things up and someone using metaphorical language to describe an ineffable, but real, experience." When I read that, I felt like this was a smuggled bit of Eugenides, a secret sentence. So – I'm trying to answer my own question here: in going back to the traditional methods of tracking characters' consciousnesses, you're trying to talk honestly about all interior conditions: not just thought processes, but desire, and madness, and mystical visions. In other words, the old Henry James problem of point of view suddenly gets aligned with the even older problem of mystical visions. Am I making sense?

JE Mystical visions are, by their very nature, indescribable. That doesn't keep people from trying to describe them, however. St Teresa found a fictional idea that allowed her to express something inexpressible. Which is what you have to do to write a novel, especially one about desire and madness.

AT But do you ever worry that words can't be mapped on to the interior? Or even: that this talk of interiors, this language of depth, doesn't work? There's something Nabokov says somewhere about Joyce: that Ulysses is a new world invented by Joyce where people think by means of words. Whereas, says Nabokov, in fact people also think in terms of pictures …

JE I'm one of those terrible literary people who doesn't feel as if I have a thought if it's not formed in words. So I guess I'm not sure that Nabokov is right there. Or at least I don't share his sense that people think in pictures.

AT This issue of pictures and thinking, of honest and precise interiors, is very much a problem when writing about sex. In The Marriage Plot you've allowed yourself more physically detailed descriptions of sex than before. The emphasis on interior precision has also created a greater, let's say mechanical, precision. And so I was wondering – what was the honesty like?

JE The Marriage Plot involves three characters recently released from college, and if I remember correctly, sex was sort of important back then. I couldn't have described their lives with any fidelity if I'd left out the sex. But how did it feel? Sometimes a bit scary. You're putting yourself on the line with some of that stuff. But, again, mainly I was just trying to present this aspect of their lives as honestly as possible.

AT I once read an interview somewhere with Sam Lipsyte, who said that the worry as a novelist wasn't that readers would think what you were describing was autobiographical. The problem was that it was constantly autobiographical on a more abstract but still terrible plane – that you were letting people follow the direction of your gaze.

JE It's not as if there is some kind of experience out there that the novelist wants to capture and describe. Writing novels is the creation of that experience itself. The way you know you've found the right narrative voice for a book is because the voice gives you access to the experience – the felt life – that is the book. The excitement of writing fiction, as fitful as it may be, comes from escaping the quotidian details of your own life, even if you're writing about things that you may have experienced. Writing novels isn't retrospective – it's current, present, incremental, day by day, as you write. Which is how a narrative voice allows you to know about things you didn't know you knew.

AT I love this idea that a novel creates the experience. Because a novel isn't self-expression, whatever that would be: but then again, it isn't some kind of matte surface of codes either. I wonder sometimes if literature is distorted by ideas of surface and depth: like form and content, or language and the real. Whereas writing a novel is closer to a performance piece, just like each individual reading.

JE Every reading is a live event. And a novel should unfold in the "present time" of each reader's reading of it. To get it to do that, smoothly, intelligibly, entertainingly, is what requires the effort, the rewriting and reworking. But yes, the surface is too much discussed and I fear having to discuss it with this book, as I know I will.

AT But the way you're talking about felt life, or experience: it's oddly vulnerable, I think, oddly exposed – which is why I like it: to want to do something so difficult and so simple.

JE Well think about your essay on Barthes. You say: "His ideal Novel, he wrote, would have the qualities of Simplicity, Filiation and Desire. And he ended with a phrase from Schoenberg – the great exemplar of the avant-garde, who refused to see the avant-garde as anything other than pure tradition. It's still possible, said Schoenberg, to write music in C Major. And that, wrote Barthes, in a lovable paraphrase, was his modest, utopian ideal: to write a work in C Major." That's a great quote, and expresses exactly the way I feel about writing fiction at this point. I dislike the wilful dissonance of so-called experimental writing and, like you, I think, I find that there are discoveries still to be made between the lines of narrative fiction. Your essay on Barthes suggested that he was coming to that conclusion, too, though he never did get to write his novel.

AT Yes, but I still believe in the value of the experimental. Sometimes I think that's all I believe in. Although the experiments I really admire are forced on novelists by something that isn't technical: the overflowing real instead. So no, it's not that I want to give up on either narrative or character – but I do want to mess them up.

JE I'm not against experimental writing, either. I'm against experiments that fail to discover anything new and that make what are now pretty standard avant-garde moves. You're right: the best experiments aren't technical. It's the need to describe something new about human experience or consciousness that drives literary innovation. Joyce's stream-of-consciousness is the perfect example. It's technically achieved but it's really an attempt at verisimilitude, at actually describing or mapping consciousness.

AT In The Marriage Plot you do something very intricate with the way the timeframes overlap: since we're always seeing the story from roughly one centre of consciousness, the reader has to keep revising what they thought was true; and also, and most movingly, the reader watches a character not know something that the reader does know. Can you describe the writing of this? How did you decide on that structure?

JE I violated the principles of the marriage plot by telling the story from three points of view. Austen would never do that. The Henry James of The Portrait of a Lady wouldn't either. But I wasn't concerned with the "plot" of the marriage plot, that is, not with who ended up with whom. I was interested in how the "marriage plot" functions today, the extent to which we've internalised ideals of romance and are controlled by them. What I learned in writing the book is that the marriage plot now plays out in our own heads. This is a rather semiotic notion, for a novel that makes a fair amount of fun of deconstruction, or at least its collegiate adherents.

I didn't decide on the structure so much as come to it little by little. I wrote the Madeleine sections first, at least the first 120 pages, and then went back and put in the Mitchell sections. I always knew that Leonard would come in later in the novel, and had that all set up.

AT Describe this "little by little" in more detail. I mean: think of the strange narrative structure of The Virgin Suicides. The five sisters' suicides are announced in the first paragraph: and so it seems that each chapter will give us a new death. Whereas in fact what follows is a long period of stasis, and then a sudden prestissimo festival of suicide at the end.

JE I came upon that structure through trial and error. At first I, too, expected to have a death every chapter, to dole out the suicides. But I quickly realised how monotonous that would be for the reader, and so I had to figure out another solution. The trick with that book was to tell the reader exactly what was going to happen in the first paragraph and then, despite that foreknowledge, to create a sense of suspense. Finally, I came up with the "festival", as you put it. The reader is getting close to the end of the book and so far only one sister has died. The reader begins to wonder, "How are they all going to die in time?" And so you have suspense, despite the previous revelations …

AT Do you abandon books? Abandon sections?

JE Every book is like that for me. I have to inch my way forward, trying out a lot of possibilities and reworking chapters until I feel the thing working, assuming the proper shape. As for my slowness, I've got another book almost finished, so will be publishing something else before too long. But I did also start a novel that I had to put aside. The Marriage Plot grew out of that book, and I followed it. I spent about three years on a novel that is now in my desk drawer. It happens.

Something you quoted from Barthes rang true to me. When he says that the death of literature haunts writers and that you have to stare the ghost in the face. I think it's pretty clear that the novel is still the best form we have for describing the complexity of human emotion and thought. Talk about maximum information: the novel has the largest bandwidth going. I was staring the ghost of the marriage plot in the face while writing this book. Being haunted by the death of literature doesn't require a wholesale scrapping of the traditional project of telling stories or creating characters, but it does require reinventing the way stories get told. Messing them up, as you put it.

I dislike convention and tired formulas as much as you do, but you don't want to lose the heart of fiction – the emotional register, the narrative pull – just to be novel. I'm like an ageing radical who decided to work inside the system.